EP0084653B1 - Mehrteilige magnetische Linse mit konzentrischen Spalten - Google Patents

Mehrteilige magnetische Linse mit konzentrischen Spalten Download PDF

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Publication number
EP0084653B1
EP0084653B1 EP82111718A EP82111718A EP0084653B1 EP 0084653 B1 EP0084653 B1 EP 0084653B1 EP 82111718 A EP82111718 A EP 82111718A EP 82111718 A EP82111718 A EP 82111718A EP 0084653 B1 EP0084653 B1 EP 0084653B1
Authority
EP
European Patent Office
Prior art keywords
lens
pole piece
piece set
pole pieces
outer pole
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP82111718A
Other languages
English (en)
French (fr)
Other versions
EP0084653A3 (en
EP0084653A2 (de
Inventor
Lee H. Veneklasen
William J. Devore
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Etec Systems Inc
Original Assignee
Etec Systems Inc
Perkin Elmer Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Etec Systems Inc, Perkin Elmer Corp filed Critical Etec Systems Inc
Publication of EP0084653A2 publication Critical patent/EP0084653A2/de
Publication of EP0084653A3 publication Critical patent/EP0084653A3/en
Application granted granted Critical
Publication of EP0084653B1 publication Critical patent/EP0084653B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/30—Electron-beam or ion-beam tubes for localised treatment of objects
    • H01J37/3002—Details
    • H01J37/3007—Electron or ion-optical systems
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/02—Details
    • H01J37/04—Arrangements of electrodes and associated parts for generating or controlling the discharge, e.g. electron-optical arrangement, ion-optical arrangement
    • H01J37/10—Lenses
    • H01J37/14—Lenses magnetic
    • H01J37/141—Electromagnetic lenses

Definitions

  • This invention relates to a composite magnetic particle beam lens. Such lenses may be used in lithography.
  • FIG. 1 illustrates a typical prior art system 10 having a composite objective lens 12.
  • a particle (electron or ion) source 14 from which is formed a beam 16 directed through a number of apertured plates 18 and blanking and focusing lenses 20 until the beam reaches the composite objective lens 12 for directing the beam onto a target 22.
  • the target 22 is a resist layer positioned on a stage 24 which moves in a direction at right angles to the deflection of the beam.
  • Figure 2 illustrates an enlarged cross-sectional view of the prior art objective lens 12 of Figure 1 and shown to comprise a pair of deflection coils 26 and 28 within the bore 30 of the lens.
  • the axial focusing field B z (z) is formed by one or more gaps 32 located between a pair of cylindrical pole pieces 34 and 36 conventionally of Ferrite material located within a solenoidal excitation lens coil 38.
  • a cylindrical outer return yoke 40 usually made of iron, surrounds the excitation coil 38.
  • the yoke as shown also encompasses the pole pieces by flanges 42 to position the pole pieces.
  • the shape of the focusing field depends upon the shape and magnetic permeability of the pole pieces. If the permeability of the pole pieces is very high, then the field shape is dominated by gap geometry. However, as the lens excitation increases, the magnetizing force H increases and the permeability decreases. This effect, known as saturation, causes magnetic flux to leak out of the pole piece and into the lens bore, causing the shape of the focusing field to change. In the case of Ferrite pole pieces where the permeability is high only over a relatively narrow range of magnetizing force, this effect is noticeable even at low excitation. Due to the critical nature of the deflection optimization one would ideally maintain the Ferrite material at constant permeability over a wide range of excitation.
  • the traditional solution to the problem is to provide very thick pole pieces, i.e., thicken the pole pieces 34 and 36 so as to provide a large cross-sectional area, to carry the magnetic load. With a sufficiently large cross section, the Ferrite material does not approach saturation.
  • This solution has several disadvantages. As well as increasing the weight, size and cost of the lens, it does not avoid the fact that the permeability of the Ferrite material changes dramatically over the operating range, resulting in small but significant changes in field shape. Since the iron portion of the lens is further removed from the bore and has a far higher saturation flux, its properties play a relatively minor role.
  • the deflection system is enclosed by a Ferrite cylinder but is not shown as magnetically connected to the iron lens cylinder.
  • the Ferrite is being used to provide a return path for the deflection field, but since only a single cylinder is used, the Ferrite is only one of the two pole pieces necessary to form a lens field. It differs from the following disclosure insofar as the deflection system cannot be located within or below the lens gap. Further, no mention is made of using the iron gap as a means of reducing saturation in the Ferrite. As drawn the design would suffer from the saturation effects mentioned above.
  • the invention accomplishes the foregoing objects in providing a composite magnetic particle beam lens comprising two nested sets of coaxial cylindrical pole pieces, each set consisting of two cylinders of magneticaly soft material having the same radius and being axially separated to form a lens gap, the lens further comprising an excitation lens coil surrounding said pole pieces, an outer return yoke of magnetically soft material surrounding said lens coil, said magnetically soft material of said yoke being different from the material of the inner pole piece set and the outer pole piece set being provided for shunting any excess flux from said excitation lens coil around said inner pole piece set, whereby said inner pole piece set consists of a ferrite material, said outer pole piece set consists of high saturation flux material, and the lens gaps formed by said inner and outer pole piece sets are axially co-extensive.
  • the excitation lens coil may be solenoidal.
  • the outer pole pieces set preferably is constructed of a high saturation material such as iron.
  • the return flux from the deflection coil may be carried by the inner cylindrical pole pieces only, while the flux generated by the lens coil is shared by the two sets of inner and outer cylindrical pole pieces but partially shunted around the inner cylindrical pole pieces.
  • the material of said outer pole pieces is the same as that of said yoke.
  • Said outer pole pieces may be in intimate radial contact with said inner pole pieces.
  • the outer pole pieces may be separated from said inner pole pieces by a radial gap.
  • Especially means like two additional radial spacers, may be provided spacing said inner pole pieces from said outer pole pieces.
  • the spacing means may comprise rings of non-magnetic material.
  • the above-mentioned composite lens may be especially useful in a particle beam lithographic system having means for generating a particle beam, means for shaping, blanking and focusing said beam and including the said composite objective lens.
  • lens excitation coils 38, deflection coils 26 and 28 and inner pole piece cylinders 34 and 36 are essentially the same.
  • second or outer cylindrical pole pieces 50A,B shown as being made of the same material and integral with the yoke 40 and containing a gap 52 located coextensive with the gap 32 in the inner pole pieces 34 and 36.
  • These pole pieces 50A, 50B may or may not be spaced as by radial gap 54 from the outer wall 56 of the inner pole pieces by step 58 formed in the outer pole piece.
  • Figure 4 shows the alternative embodiment of the invention in which the inner pole piece, is provided with a non-magnetic spacer 60 located between the inner and outer pole pieces.
  • the spacer 60 not only allows the inner pole piece to be magnetically isolated but also replaces the function of the step 58 of the embodiment of Figure 3.
  • This spacer 60 is only functional if the radial gap 54 is used also, the effect of both spacer 60 and radial gap 54 being to magnetically isolate the Ferrite structure. While only one corner of the lens is shown, obviously the spacer is cylindrical and there is a similar spacer at the lower end of the inner pole piece also.
  • the spacer controls that portion of the total focusing field flux that is conducted by the inner pole piece and prevents any deflection field from returning through the yoke.
  • Figure 5 shows alternative versions of the composite lens system.
  • Figure 5 illustrates one of the inner pole pieces, i.e., 34, and outer pole piece 50A as being contiguous with the outer cylindrical walls 56 of the inner pole piece, containing no radial gap.
  • the action of the composite lens is generally as follows: At low excitation, the permeability of the Ferrite of the inner pole pieces 34 and 36 is greater than or equal to that of the iron outer pole pieces 50A, 50B and the lens field is determined by the geometry of the inner surface of the Ferrite inner pole pieces. With increasing excitation, the permeability of the Ferrite inner pole piece attempts to drop below that of the iron so that excess flux is shunted through the gap between the iron outer pole pieces 50A, 50B. Since this latter gap has a geometry very similar to that of the Ferrite inner pole piece, the portion of the lens field due to this gap is nearly the same shape. If the Ferrite inner pole pieces were completely saturated, then the lens field would still maintain a similar shape.
  • the permeability of the inner Ferrite pole pieces never drops far below that of the iron, because its magnetizing force H is limited by the alternate path provided by the outer pole piece that conducts the excess flux.
  • the permeability of the inner pole pieces cannot drop far below that of the outer pole pieces.
  • the field on the axis of the lens is still largely determined by the shape of the inner contours of the inner pole pieces.

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  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Electron Beam Exposure (AREA)

Claims (7)

1. Mehrteilige magnetische Teilchenstrahllinse (12) mit zwei ineinandergeschachtelten Sätzen koaxialer zylindrischer Polstücke (34, 36, 50A, 50B), wobei jeder Satz aus zwei Zylindern aus magnetisch weichem Material besteht, die den gleichen Radius aufweisen und axial getrennt sind, um einen Linsenspalt (32, 52) zu bilden, gekennzeichnet durch eine die Polstücke umgebende Erregerlinsenspule (38), ein die Erregerlinsenspule umgebendes Rückflußjoch (40) aus magnetisch weichem Material, wobei das Material des Joches (40) von dem Material des inneren Polstücksatzes (34, 36) verschieden ist und der äußere Polstücksatz (50A, 50B) vorgesehen ist, um jeden Überschußfluß von der Erregerlinsenspule (38) um den inneren Polstücksatz (34, 36) herum zu shunten, wodurch der innere Polstücksatz (34, 36) aus einem Ferritmaterial besteht, der äußere Polstücksatz (50A, 50B) aus einem Flußmaterial hoher Sättigung besteht und die durch den inneren und den äußeren Polstücksatz gebildeten Linsenspalte (32, 52) sich koaxial erstrecken.
2. Linse nach Anspruch 1, dadurch gekennzeichnet, daß das Material des äußeren Polstücksatzes (50A, 50B) das gleiche ist wie das Material ders Joches (40).
3. Linse nach Anspruch 1, dadurch gekennzeichnet, daß der äußere Polstücksatz (50A, 50B) in engem radialen Kontakt mit dem inneren Polstücksatz (34, 36) steht.
4. Linse nach Anspruch 1, dadurch gekennzeichnet, daß der äußere Polstücksatz (50A, 50B) von dem innere Polstücksatz (34, 36) durch einen radialen Spalt getrennt ist.
5. Linse nach Anspruch 1, gekennzeichnet durch eine Einrichtung (60), welche den inneren Polstücksatz (34, 36) im Abstand von dem äußeren Polstücksatz (50A, 50B) hält mittels zweier zusätzlicher radialer Abstandhalter (60).
6. Linse nach Anspruch 5, dadurch gekennzeichnet, daß die Abstandhalteeinrichtung (60) Ringe aus nichtmagnetischem Material umfaßt.
7. Teilchenstrahl-Lithografiesystem, das eine Einrichtung zur Erzeugung eines Teilchenstrahls und eine Einrichtung zum Formen, Austasten und Fokussieren des Strahles umfaßt mit einer mehrteiligen Objektivlinse, wobei die Objektivlinse eine mehrteilige magnetische Teilchenstrahllinse nach Anspruch 1 ist.
EP82111718A 1982-01-26 1982-12-17 Mehrteilige magnetische Linse mit konzentrischen Spalten Expired - Lifetime EP0084653B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US342696 1982-01-26
US06/342,696 US4469948A (en) 1982-01-26 1982-01-26 Composite concentric-gap magnetic lens

Publications (3)

Publication Number Publication Date
EP0084653A2 EP0084653A2 (de) 1983-08-03
EP0084653A3 EP0084653A3 (en) 1986-04-16
EP0084653B1 true EP0084653B1 (de) 1990-03-14

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP82111718A Expired - Lifetime EP0084653B1 (de) 1982-01-26 1982-12-17 Mehrteilige magnetische Linse mit konzentrischen Spalten

Country Status (3)

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US (1) US4469948A (de)
EP (1) EP0084653B1 (de)
JP (1) JPS58129734A (de)

Families Citing this family (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2597259A1 (fr) * 1986-04-15 1987-10-16 Thomson Csf Dispositif a faisceau electronique pour projeter l'image d'un objet sur un echantillon
US5311028A (en) * 1990-08-29 1994-05-10 Nissin Electric Co., Ltd. System and method for producing oscillating magnetic fields in working gaps useful for irradiating a surface with atomic and molecular ions
US5338939A (en) * 1992-01-13 1994-08-16 Fujitsu Limited Charged particle beam exposure including a heat blocking partition positioned near deflecting coils
US5438203A (en) * 1994-06-10 1995-08-01 Nissin Electric Company System and method for unipolar magnetic scanning of heavy ion beams
US5481116A (en) * 1994-06-10 1996-01-02 Ibis Technology Corporation Magnetic system and method for uniformly scanning heavy ion beams
US5672879A (en) * 1995-06-12 1997-09-30 Glavish; Hilton F. System and method for producing superimposed static and time-varying magnetic fields
US5729022A (en) * 1996-09-26 1998-03-17 Etec Systems, Inc. Composite concentric-gap magnetic lens and deflector with conical pole pieces
US6677599B2 (en) * 2000-03-27 2004-01-13 Applied Materials, Inc. System and method for uniformly implanting a wafer with an ion beam
US6661016B2 (en) 2000-06-22 2003-12-09 Proteros, Llc Ion implantation uniformity correction using beam current control
US6768117B1 (en) * 2000-07-25 2004-07-27 Applied Materials, Inc. Immersion lens with magnetic shield for charged particle beam system
US9620327B2 (en) * 2014-12-26 2017-04-11 Axcelis Technologies, Inc. Combined multipole magnet and dipole scanning magnet
JP6480534B1 (ja) * 2017-09-26 2019-03-13 株式会社ニューフレアテクノロジー 荷電粒子ビーム照射装置及び基板の帯電低減方法
TWI744671B (zh) * 2018-08-03 2021-11-01 日商紐富來科技股份有限公司 電子光學系統及多射束圖像取得裝置
US11114270B2 (en) * 2018-08-21 2021-09-07 Axcelis Technologies, Inc. Scanning magnet design with enhanced efficiency

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
UST927524I4 (de) * 1952-09-09
DE1033818B (de) * 1954-06-18 1958-07-10 Siemens Ag Magnetische Elektronenlinse
US3396299A (en) * 1964-06-15 1968-08-06 Jeol Ltd Magnetic flux leakage guide for magnetic electron lenses
US3801792A (en) * 1973-05-23 1974-04-02 Bell Telephone Labor Inc Electron beam apparatus
US3984687A (en) * 1975-03-17 1976-10-05 International Business Machines Corporation Shielded magnetic lens and deflection yoke structure for electron beam column

Also Published As

Publication number Publication date
JPH0441463B2 (de) 1992-07-08
EP0084653A3 (en) 1986-04-16
US4469948A (en) 1984-09-04
EP0084653A2 (de) 1983-08-03
JPS58129734A (ja) 1983-08-02

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